Casting is a plastic film production process, which first plasticizes and melts the raw materials through an extruder. The film is extruded through a T-shaped structure forming die, and cast in a sheet shape onto the roller surface of a smoothly rotating cooling roller.

The film formed by the casting method has a uniform thickness, better transparency and better heat-sealability than the blown film. The thickness is in the range of 0.005-1mm. It is generally used for packaging dry biscuits and melon seeds, as a heat-sealing layer substrate for composite materials and various construction waterproof materials.